Fluid-conducting connections serve to connect pneumatic and/or hydraulic systems that are pressurized. The fluids to be conducted may be, for example, gases and/or liquids. Such connections are arranged in the field of fitting technology, which distinguishes substantially between non-releasable press-fit connections and releasable plug type connections. The present invention is directed toward releasable connections which may be easily disconnected and reconnected.
The decision to use a particular type of fitting within the releasable connection types for a specific industrial application may be made, for example, on the basis of the pressure and/or temperature ranges anticipated. The type of the fluid to be conducted is also significant in order to be able to ensure leak-free operation. Though some prior art fittings manage with a sealing action produced purely by metal, in the case of high-pressure systems (more than 70 MPa, for example) may require additional sealing means.
Depending on the application, it is advantageous to carry out the construction of such a connection with a “smooth” tube. This means that the end of the tube that makes the connection has a uniform outer diameter. In this instance, the term “smooth” tube or a tube having a “uniform outer diameter” is intended to mean one which has consistent, cylindrical outer surface over at least the portion thereof which is to be used in making the connection. Accordingly, the outer surface of the tube does not comprise any projections and/or protrusions required for making the connection, such as, for example, a flange, a collar, a swage, or a flare. It is also necessary to distinguish therefrom, for example, extents which taper and/or are conical. In other words, such a smooth tube having a uniform outer diameter means the free or distal end portion thereof is a typical straight tube.
Generally, the plug-type connections previously known in conjunction with a sealing ring for forming a fluid-conducting connection having a tube which has a uniform outer diameter also does not afford any possibility for the direct connection thereof to a connection component in the form of a system component such as, for example, a tank or a filter. This is substantially a result of the configurations of such system components which primarily provide for the connection piece as an intermediate coupling. Consequently, such configurations require a screw member which may be in the form of a nut having an inner or female thread and which engages a male thread formed around an outer circumferential surface of the connection component.